Liquid-crystal lenses have the potential to serve as components used in optical image formation, in sensors, and in similar applications. This is due the properties of liquid-crystal lens, such as a small volume (i.e. thin shape), an electrically-tunable optical zoom, a fast response, and low energy consumption. A liquid-crystal lens includes liquid-crystal material and a lens device, which should be collocated to achieve the desired effect. The birefringence and viscosity of the liquid-crystal material directly influence the focal length and the electrically-tunable speed of the lens. Conventional liquid-crystal materials usually have a birefringence of less than 0.2. A liquid-crystal material with a birefringence greater than or equal to 0.25 should be developed to satisfy the optical requirements of such a lens. In addition, a lens with a conventional mechanical voice coil motor has a slow focusing speed, whereas a liquid lens has the advantage of a fast electrically-tunable zoom speed. Liquid-crystal with a low viscosity may accelerate the driving electric field. In the design of a lens, the conventional concentric ring electrodes require a plurality of etching and lithography processes, and different voltages are independently applied to each of the concentric ring electrodes. Too many electrodes may result in optical leakage of the lens, thereby reducing the optical signals. Accordingly, a liquid-crystal material with excellent optical-electrical properties is called for, and the processes for fabricating the electrodes should be simplified to efficiently make the liquid-crystal lens be more competitive.